Process for electrolytic deposition of metals.



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UNI-TED 'sTA'TEs PATENT oF IcE."

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To. aHQwhom it may concern: lij altknown :thatl, FRAnK-C. MATHERS, a citizen of the Unlted States, residing at Bloomington, in the county of Monroe and State of Indiana, have invented a new and useful Process. for the Electrolytic Deposition of Metals, which the following is a specification.

soluble anode like platinum inwhich case the metal that isdeposited upon the cathode comes from the bath which'may *be brought back to the proper strength in any suitable manner. To. form insoluble salts off-the metals or alloys, the metal or alloy" whose insoluble salt is to be formed is used as anode material in an electrolyte containing a salt or salts of perchloric acid or perchloricacid or a mixture of perchloric acid and a, salt or salts of perchloric acid. Upon electrolysis the anode material dissolves and the insoluble salt may be prepared by precipitating this soluble perchloratethus formed with a suitable reagent.

- It is very desirable that a plating or refining bath should be made from saltsand acids that are very soluble in water, that are stable, that is are neither. oxidized nor reduced by electrolysis and are unchanged by the air etc, that give good deposits upon the cathode and that give good efiiciencies of corrosion at the anode and of deposition upon the cathode. Perchloric acid (HClOQ and its salts (RS10 fulfil these demands in a satisfactory manner. Perchlorates of the heavy Inetalsare very soluble in water so that solutions maybe prepared of almost any desired strength up to one part of saltin one part of Water in many cases'which is much be: yond an concentration that is ever used-in commercial plating or refining by electrolysis. The acid radical of perchloric acid and of perchlorates is very stable,-it is not reduced even by a zinc-copper couple neither is it oxidized under any conditions. It is only decomposed when ignited or fused, a

treatment to which it need not be subjected in the process described in this s ecification. The current eificiency at both e ectrodes is almost theoretical. The deposits upon the 1 m massessment. Patented Aug. 24 1909. a pearance A ril. 21. 1911 semina- 491,319.

Isfining and who understands how to use the knowledge that is commonly practiced in these arts. For. example: The solution should be circulated or stirred to prevent undue changes in concentration. The solution should be of the proper concentration and should contain the proper amount of free acid. I prefer a bath containing from 5 to '10 per cent. of metallic perchlorate and from 2 to 5 per cent. of free perchloric acid,

with such metals as copper, lead, silver, etc.

which are easily deposited while with zinc, cadmium, etc. a lower concentration of acid shouldbe used. If'an adherent protective deposit is desired upon the cathode, the cathode should be clean and free from grease. If it is desired to strip the deposited metal from the cathode, a greased cathode should be employed. The addition of small quantities of certain substances greatly improves the character of the deposit in regard to smoothness, brightness, and denseness. The beneficial effects of these substances have been long known and are described in many books and original articles upon the subject.- Among the substances that have been suggested as additions to the bath are :arsenious acid, stannous chlorid, .(Watt Electrometallw'gy, 1895, page 46) carbon disulfid, collodion, iodin andguttapercha in chloroform, etc. MMillen, A Treatise on Electrometallm'gy 1890, page 9). Experiments in connection with this work have shown that tannin is also an excellent addition substance. I prefer to use from 0.1 to 0.4 per cent-.. of these substances. The current .density must be regulated depending upon the concentration of the solution, the amount of free acid that is'present, the temperature, the amount of stirring, the nature of the ,metal that is to be plated or refined, etc. I

depositing metals which consists in subjectas'new and desire to secure anode to an electric current in a solution containing salts of perchloric acid and in electrodepositing the metal upon the cathode substantially as described.

3. That improvement in the art of electrodepositing metals which consists in subjecting the metal or an alloy of the metal as ano e to an electric current in a solution containing a salt of perchloric acid and of free perchloric acid and in electrodepositing the metal upon the cathode substantially as described.

4. That improvement in the art of electrodepositing metals which consists in subjecting the metal or an alloy of the metal as anode to an electric current in a solution containing salts of perchloric acid and of free perchloric acid and in electrodepositing the metal upon the cathode substantially as de- I scribed.

5. That improvement in the art of electro depositing metals which consists in subjecting to an electric current a solution containing a salt of perchloric acid and in electrodepositing the metal contained in said salt' upon the cathode substantially as described.

6. That improvement in the art ofelectrodepositing metals which consists in subjecting to an electric current a solution containing salts of perchloric acid and in electrodepositing the metal contained in said salt upon the' cathode substantially as described.-

7. That improvement in the art of electrodepositing metals which consists in subjecting to an electric current a solution containing a salt of perchloric acid and of free perchloric acid and in elec'trodepositin the metal contained in said salt upon the cat ode substantially as described.

8. That improvement in the art of electrodepositing metals which consists in subjecting to an electric current a solution containing, salts of perchloric acid and of free pe'rchloric acid and in electrodepositing the metal contained in said salt'upon the cathode substantially as described.

Witnesses THOMAS J. SAR'E, ROBERT E. LYONS.

FRANK o. MATHERS. i 

